Handy.js

Find type

export const isObject = (value) => value !== null && typeof value === "object";
export const isFunction = (value) => typeof value === "function";
export const isString = (value) => typeof value === "string";
export const isBoolean = (value) => typeof value === "boolean";
export const isNumber = (value) => typeof value === "number";
export const isUndefined = (value) => typeof value === "undefined";

Number

export const range = (min, max) => [...Array(max - min + 1).keys()].map((i) => i + min);

Object

const pickByKeys = (obj: { [key: string]: any }, keys: string[]) => {
  return keys.reduce<{ [key: string]: any }>((acc, key) => {
    if (obj && obj.hasOwnProperty(key)) {
      acc[key] = obj[key];
    }
    return acc;
  }, {});
};